Scientists Make Temperature Sensor From Tobacco Cells

Scientists and engineers love copying nature, there is even a term for it, biomimicry. Evolution has usually had thousands, millions, if not billions of years to perfect a mechanism, so it's usually pretty good. Sometimes it's so good, that we actually skip the mimicking part of biomimicry and just use living organisms.

A group based in Switzerland did just that, creating a hybrid material that is the most sensitive temperature sensor on record. (via EurekaAlert) The scientists knew that plants have a very good method for detecting and reacting to temperatures. They didn't know exactly how it worked, but they knew it resulted in a change in electrical conductivity within the cells. So they needed a way to tap into that change in conductivity while keeping the cells stable.

Living plant cells aren't exactly the most convenient thing to work with, requiring water, direct sunlight, and micronutrients. To get around this issue, they had to kill the plant cells. Specifically, tobacco cells that they grew in culture containing a bunch of carbon nanotubes. The nanotubes were able to penetrate the plant cell wall and take up most of the cells volume. Drying this combination resulted in a hybrid material that the scientists have dubbed cyberwood.

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The plant cells may be dead but their temperature sensing capabilities amazingly remained. It's estimated that the cyberwood-based sensor is 100 times more precise than current sensors. Any change in temperature, even the slight warmth of a hand a few centimeters away, results in a very measurable change in electrical conductivity.

The group is already applying for a patent, but they are actually attempting to understand the mechanism so that they can build a sensor without growing plant cells. After some careful analysis they determined that the main driver behind this ability is pectin. You may be familiar with pectin as the primary thickener of jams and jellies; it's a complex sugar molecule that can cross-link to form gels. Naturally occurring pectin gels in plant cell walls can contain ions, and the gel weakens slightly as the temperature increases. The ions can move more freely as the gel weekends. and this increases the overall conductivity of the cell, and consequently the cyberwood.

Incorporating highly conductive carbon nanotube simply boosts this effect and makes it more detectable. With this discovery the next step is to build a sensor from just nanotubes, pectin., and ions. Such sensitive sensors could have a wide range of applications including gesture control interfaces and infrared cameras.